The invention is directed to a glycated potato protein, a food product comprising a glycated potato protein, an additive comprising a glycated potato protein and a method for preparing a glycated potato protein.
The ingestion of certain foods is associated with a dry, puckering sensation in the mouth known as astringency. An astringent taste may alternatively be described as a peculiar smell or an unpleasant taste, thereby giving a filmy mouthfeel and graininess. Astringency tastes unpleasant to many mammals, including humans. It has been proposed that astringency is associated with the interaction of certain compounds with salivary proteins in the mouth. Compounds may for example denature, bind and/or precipitate the salivary proteins, thus causing the astringent taste.
Some protein-containing food products are known to have astringency, in particular when such food products are acidic. Known examples of such food products are protein-containing acidic foods or drinks such as fermented milk beverages and other sour milk beverages and also sports drinks. The degree of astringency in protein-containing food products may vary depending on the type of protein used.
A further problem of protein-containing food products is the solubility of the protein. Especially at low pH, protein tends to precipitate due to decreased solubility in the liquid. This may lead to a stronger astringent taste. Furthermore, in certain aqueous drinks, such as sports drink and soft drinks, a suspension is often regarded by the customer as unappealing.
Whey proteins are generally preferred for use in acidic protein-containing food products for several reasons. Compared to most other proteins, whey proteins have a relatively mild astringent taste. Furthermore, whey proteins have a good solubility in water, although precipitation still occurs in solutions with a very low pH (e.g. a pH lower than 4). Because of the good solubility, whey protein may also be used in clear and/or transparent beverages.
There are however some disadvantages of using whey protein in food products. First, whey protein has a taste of its own which is often experienced as unpleasant. Furthermore, some people are allergic to whey protein. Whey protein is further not suitable in a vegan diets, since it is produced from milk-products. Also, whey proteins are relatively expensive.
Methods are known in the art to relieve the astringency of an aqueous solution comprising dissolved proteins by modification of the proteins. Examples of such protein modification methods are phosphorylation, hydrolysis, transglutamination and glycation. A disadvantage of such methods is that the modification may often lead to a decreased solubility of the protein in the solution, a change in colour in the solution and/or an undesirable flavour (off-taste) of the solution.
EP-A-1 698 239 describes an acidic food or drink comprising an acidic-soluble protein and one or more of salts or saccharides selected from the group of astringency relieving agents consisting of water-soluble polysaccharides, water-soluble basic salts, alkali metal salts of organic acids, basic monosaccharides and basic oligosaccharides. The presence of the one or more salts or saccharides is said to relieve the astringency of the food or drink. An example of a suitable saccharide is maltodextrin. An acidic protein beverage according to EP-A-1 698 239 may be prepared by adding a powder material containing the acidic-soluble protein and the one or more of salts or saccharides as a raw material to a beverage.
A disadvantage of the method described in EP-A-1 698 239 is that the astringency relieving agents mentioned are not all able to suitably decrease the astringency of all protein solutions. For example, it was found that maltodextrine was unable to suitably decrease the astringency of a potato protein solution. Furthermore, a disadvantage of using a basic monosaccharide or a basic oligosaccharide as an astringency reducing agent is that an uncontrolled Maillard reaction may occur between the protein and these sugars, which may lead to an off-taste and/or undesirable, usually brown, colouring of the solution. A further disadvantage is that the solubility of the protein may be decreased by addition of reducing sugars.
WO 2009/117572 discloses a method for producing protein-polysaccharides conjugates comprising reacting a polysaccharide comprising a reducing sugar and a protein in an aqueous solution comprising 10-14% (w/v) polysaccharide and 1-30% (w/v) protein at a temperature of 40-120° C. Thus, the method makes use of a wet heat treatment. The protein may be a whey protein or a soy protein and the polysaccharide comprises a reducing sugar that may be chosen from the group of glucose, fructose, glyceraldehyde, lactose, arabinose, maltose, maltodextrin and dextran.